Testing leptin, has the range changed?
When I wrote my book, there was only one lab testing leptin that used a radioimmunoassay that is quite accurate. As leptin has become more popular, largely as a result of having written the book, many labs are now testing it. However, since radioimmunoassay is a more expensive test, and generally done for research purposes, and requires a license to handle radioactive materials, most labs have now gone to a different ELISA enzyme methodology of testing that has different standards though the actual numbers are fairly similar. I would use the latest reference ranges.